That is exactly right. It’s a population-average that is meant to give a good experience to the largest possible number of consumers and be possible to implement with a single (non-personalized) physical design that will be mass-produced. True neutrality requires personalization of the headphone response to each user, like what is done in the Smyth Realiser or like the more work-intensive manual solution from dr. Griesinger: https://www.youtube.com/watch?v=1VaKZr208Dc
None of these fixed-curve solutions like Harman, Olive&Welti or anything based on them like Oratory’s EQ curves, Sonarworks, Toneboosters, nothing like that is truly neutral to most people. Only personalized solutions are truly neutral.
No, that’s a headphone response curve, it should always be “V-shaped” like that because it’s supposed to compensate for various changes that happen when the sound no longer passes around your face and over your pinna but is shot directly into your ears. “Flat” is what the curve should look like when you’re measuring good speakers in an anechoic chamber, but for headphones to sound like that they have to have a different response, more like what you’re seeing on the Harman graph. More discussion here: